CA2054918A1

CA2054918A1 - Separator/folder bag machine

Info

Publication number: CA2054918A1
Application number: CA002054918A
Authority: CA
Inventors: Peter J. Hatchell; Ronald L. Lotto; Ernest H. Teske; Donald J. Bauknecht
Original assignee: Individual
Current assignee: FMC Corp
Priority date: 1990-11-09
Filing date: 1991-11-04
Publication date: 1992-05-10
Also published as: AU8697291A; ES2069453A1; AU670492B2; AU657281B2; IT1251703B; BE1005517A5; BR9104870A; FR2669575A1; AU669779B2; JPH04284231A; AU5916294A; DE4135786A1; ES2069453B1; AU5916094A; ITMI912957A0; FR2669575B1; US5388746A; JP2694193B2; ITMI912957A1

Abstract

ABSTRACT OF THE DISCLOSURE
A separator/folder bag machine for developing individual, folded, plastic bags. A pair of high speed separation rollers, actuated by means of a servo motor driven eccentric linkage, engages a continuous plastic web to separate individual plastic bags formed in the web. A pair of parallel, wide belts, and a pair of similar, overlying belts, engage both sides of the separated bags and transport the bags to a plurality of folding stations. Air jets at selected locations in the folder/separator controllably direct the bags through pairs of nip rolls to fold the bags along predetermined fold lines. Sensors in the folder/separator sense abnormal conditions and deactivate particular fold stations to reject improperly formed bags. A two speed slowdown mechanism at the discharge end of the separator/folder slows the folded bags to facilitate downstream handling. An optional stacker and indexing conveyor automatically stacks predetermined numbers of folded bags, aligns and compresses the bags to form an easily handled stack, and conveys the formed and compressed stack to downstream apparatus for further handling.

Description

` -1- 76 _111972 ~ 8 SEPARATOR/FOLDER BAG MACHINE
SPECIFICATION

This invention relates generally to bag making 5 machilles and, more particularly, to separator/folder mechanisms for separating and folding plastic bags in a bag making op~ration.
Plastic bags of various types are in widespread use throughout the world. Such bags can be economically manufactured in large quantities from 10 extruded plastic films, and a variety of machines have been developed for automating the bag making process. Every advancement that makes it possible to produce bags with greater speed and efficiency results in greater savings to the manufacturers and 15 users of plastic bags.
Plastic bags are typically formed from a continous plastic web that can be in the form of a flattened continuous tube or a continuous folded - sheet. By forming bottom welds, in the case of a 20 tubular web, or side welds, in the case of a folded web, individual bags are defined. Typically, a perforation adjacent the bottom or side welds allows separation of the individual bags. Until separation, the bags remain strung together in a continuous 25 ribbon.
For a variety of reasons, additional processing is often necessary before the bags can, as a practical matter, be offered for sale. For example, a typical run of bags may include far more bags than 30 any one consumer could possible require At one time.
` In addition, the need to separate the bags manually could detract from the bags' convenience and overall utility. Finally, in the case of larger bags, such as lawn and trash bags, the sheer size of each bag 20~918 makes handling and packaging difficult unless the bags are first folded down to a more manageable size. Accordingly, a variety of machines have been developed for automatically separating, folding and 5 stacking plastic bags formed from continuous plastic webs.
In one prior machine, bag separation was accomplished by operating a downstream set of nip or separation rollers at a higher speed that an upstream 10 set of rollers. As the perforated web encountered the downstream separation rollers, the higher speed of the rollers pulled the web, thereby tearing it along the perforations. A pneumatic cylinder periodically cycled the high speed separation rollers 15 inLo contact with each other to initiate the separating sequence. Although effective, the use of a pneumatic cylinder to cycle the separation rollers limited the maximum machine operating speed and caused inaccuracies in the separation spacing.
In one prior machine, a plurality of rope belts were used ~o convey the separated bags between the separating nip rolls and a number of downstream ~olding stations. During operation, it was not uncommon for the side edge of a bag to wrap itself 25 around one of the ropes. This caused jams and ; required that the machine be shut down while the jam was cleared. Valuable production time could thus be lost.
In view of the foregoing, it is a general object 30 of the present invention to provide a new and improved machine for separating and folding articles formed from a continuous plastic web.
It is a further object of the present invention to provide a new and improved separating and folding 35 apparatus that can perform separations with accuracy at high speeds.

20~91~

It is a still further object of the present invention to provide a new and improved separating and folding mechanism that can handle a variety of product widths without frequent jamming.
SUMMARY OF THE INVENTION
The invention provides a separator for separating individual sheets from a continuous plastic web having transverse perforations formed therein. Tl~e separator comprises an infeed mechanism for advancing 10 the plastic web at a predetermined speed and further cvmprises a pair of nip rollers located downstream of the infeed mechanism and mounted for reciprocating movement into and out of engagement with each other.
The nip rollers operate when engaged to advance the 15 plastic web at a speed greater than the predetermined speed so as to cause the continuous plastic web to separate along the next adjacent transverse perforation between the nip rollers and the infeed mechanism. A linkage, including an eccentric, is 20 coupled to at least one of the nip rollers for reciprocating the nip rollers into engagement with each other in response to rotation of the eccentric.
A motor is provided for rotating the eccentric to reciprocate the nip rollers into engagement with each 25 other and thereby cause the plastic web to separate along the next adjacent downstream perforation.
- The invention also provides a separator/folder for separating individual sheets from a continuous plastic web having transverse perforations formed 30 therein and for folding the separated individual sheets along at least one predetermined fold line.
The separator/folder comprises a separator mechanism for separating individual sheets from the continuous plastic web and further comprises a plurality of fold - 35 stations operable to fold the separated, individual sheets along predetermined fold lines. A plurality , .

_4_ 2~349~ g of belts are provided for conveying the separated individual sheets between the separator mechanism and the fold stations. Each of the belts defines a conveying surface having a width greater than the 5 width of the separated individual sheets and includes a continuous side margin that extends beyond the adjacent side margin of the conveyed individual sheets.
The invention also provides a separator~folder 10 for separating individual sheets from a continuous plastic web having transverse perforations formed therein and for folding the separated individual sheets along at least one predetermined fold line.
The separator/folder comprises a separating mechanism lS for separatin~ individual sheets from the continuous plastic web and further includes a plurality of fold stations operable to fold the separated, individual sheets along predetermined fold lines. The separator/folder further includes a belt assembly for 20 conveying the separated individual sheets between the separator mechanism and the fold stations. The belt assembly comprises a first belt having an undersurface and an upper surface for supporting, on ~he upper surface, the separated individual sheets.
25 The belt assembly further includes a second belt having an undersurface overlying the first belt so as to sandwich the separated individual sheets between the upper surface of the first belt and the lower surface of the second belt. Means are provided for 30 simultaneously moving the first and second belts in conjunction with each other so as to transport the separated individual sheets between the first and second belts with substantially no relative longitudinal movement between the upper surface of 35 the first belt and the separated individual sheets, and between the lower surface of the second belt and ` ~5~ 2~ 8 the separated individu~l sheets. The moving means includes a first roller engaging the lower surface of the first belt and further includes a second roller displaced from the first roller and engaging the S lower surface of the second belt. The first and second rollers are arranged to change the direction of the first and second belts and to separate the first and second belts during the change of direction so that relative differences in the longitudinal 10 surface velocities of the first and second belts over - the change of direction Are not imparted to the conveyed, separated, individual sheets.
The invention further provides a separator/folder for separating individual sheets from a continuous 15 plastic web having transverse perforations therein and for folding the separated individual sheets along at least one predetermined fold line. The separator/folder comprises a separator mechanism for separating individual sheets from the continuous 20 plastic web, and further comprises a plurality of fold stations operable to fold the separated individual sheets along predetermined fold lines. A
belt assembly is provided for conveying the separated individual sheets among the separator mechanism and 25 the fold stations. A slowdown mechanism is positioned downstream of the fold stations and functions to slow the conveyed speed of the separated, individual sheets as the sheets are discharged from the separator/folder. The slowdown 30 mechanism includes a pair of nip rolls positionsd to engage the separated, individual sheets as the sheets are discharged from the separator/folder. The slowdown mechanism further includes driving means coupled to the nip rolls for operating the nip rolls 3s at a first predetermined speed when one of the separated, individual sheets first engages the nip

2~A~8 rolls, and for reducing the speed of the nip rolls to a second predetermined speed slower than the first predetermined speed as each of the sheets transits through the nip rolls. Following discharge of the 5 sheet, the driving means increases the speed of the nip rolls to the first predetermined speed prior to engagement of the next following sheet with the nip rolls.
BRIEF DESCRIPTION OF TH~ PR~NGS
The features of the present invention which are believed to be novel are set forth with particularity in the appended c]aims. The invention, together with tl~e further objects ar~d advar~tages thereof, may best be understood by reference to the following 15 description taken in conjunction with the ` accompanying drawings, wherein like reference numerals identify like elements, and wherein:
FIGURE l is a simplified side elevation view of a ~ag making production line including a 20 separator/folder embodying various features of the invention.
FIGURE 2 is a simplified perspective view of the separating, conveying and folding mechanisms of the ; separator/folder shown in FIG. l.
FIGURE 3 is a side elevation view of the separator/folder shown in FIG. l.
FIGURE 4 is an enlarged, fragmentary, side elevation view of the folding stations included in the separator/folder shown in FIG. l.
FIGURE 5 is a simplified perspective view of the drive linkages for actuating various elements of the separator/folder shown in FIG. l.
FI5URE 6 is a top plan view of a conveyor belt incorpo~ated in the separator/folder and constructed 35in accordance with one aspect of the invention.

` ~ 7~ 2 0 ~

- FIGURE 7 ~s d~agramat~c representat~on of thefold~ng sequence performed by the separator/folder shown in FIG. l.
FIGURE 8 ~s a stmpl~f~ed perspect~ve vtew of a stacker and conveyor mechantsm for handltng separated and folded bags developed by the separator/folder.
FIGURE 9 ~s a perspect~ve vlew of one port~on of the stacker mechan~sm shown tn FIG. 8, useful ~n understand~ng the operat~on of the stack~ng f~nger mechan~sm that funct70ns to lower a stack of folded bags onto a conveyor.
FIGURE lO ~s a perspect~ve vtew of a port~on of the bag stacker useful ~n understand~ng the construct~on and operat~on of a compress~ng mechan~sm for compress~ng a stack of folded bags.
FIGURE ll ts a s~de elevat~on v~ew of the bag stacker shown ~n FIGS. 8-lO.
FIGURE 12 ~s a s7mpl~f1ed perspect1ve v~ew show1ng the dr~ve l~nkage for actuat~ng the stacker f~nger mechan~sm.
F~GURE 13 7s a perspect~ve v~ew show~ng the dr~ve mechan~sm for operat~ng the stack conveyor.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referr~ng to the draw~ngs and, ~n part~cular to FIG. l, a bag mak~ng product~on l~ne lO ~s 111ustrated. In the 111ustrated embod~ment, the product10n ltne lO funct~ons to convert a cont~nuous, tubular, plast~c web 12 lnto stacks of ~nd7v~dual, folded plast1c bags 22. The product~on l~ne ~ncludes a dr~ven unw1nd mach~ne 14 of known construct10n that conta~ns a supply roll 16 of the cont~nuous, tubular, plasttc web. The unw~nd mach~ne 14 unw~nds the web from the roll and d~scharges ~t through a dancer mechan~sm 18 that funct~ons to keep a substant~ally constant tens~on on the d~scharged web.

''~ ' , .

_ 8~ 8 From the unw1nd mach~ne, the web 12 1s fed ~nto a rotary bag mach1ne 20 of known construct~on. The rotary - bag mach1ne forms a plural~ty of regularly spaced, transverse, bottom welds across the web. Ind1v1dual bags 22 are def1ned between the spaced bottom welds.
Follow1ng format~on of the bottom welds, the web passes through a pluraltty of fold1ng boards that fold the s1de edges of the web lnwardly along fold l~nes extend~ng parallel to the long~tud1nal ax~s of the web. The w1dth of the web as 1t leaves the bag mach~ne 1s thus reduced constderably. A perforat1ng mechanlsm or kn~fe ad~acent the output of the bag mach1ne 20 perforates the web 12 1mmed1ately downstream of each bottom weld to perm~t separat~on of the tndtv1dual bags 22. The bags rema~n connected ln a cont1nuous r1bbon or web 12, however, as they leave the bag mach1ne 20.
From the bag mach~ne 20, the welded, folded and perforated web 12 1s fed to a separator/folder mach~ne 28 constructed 1n accordance w1th var~ous aspects of the 1nvent~on. The separatortfolder 28 funct10ns to separate the cont~nuous plast~c web 12 along the perforat~ons ~nto ~nd~v1dual bags 22 and then to fold the 1nd~v~dual bags 22 along predeterm1ned fold 11nes extendtng across the w1dth of each bag 22. From the bag mach~ne 28, the folded bags 22 are del1vered to a bag stacker and ~ndex1ng conveyor 30. The bag stacker and 1ndex1ng conveyor 30 stacks the folded bags 22 1n predeterm~ned numbers and transfers the stacks downl~ne for further process1ng.
Referr1ng to FIG. 2, the separator/folder mach~ne 28 1ncludes, 1n comb1nat1On, a separator mechan1sm 32 for separat1ng the 1nd~v~dual bags, a plural1ty of fold stat1Ons 34, 36 and 38 for fold1ng the bags 22 across predeterm1ned fold 11nes and a , ':
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conveyor mechan~sm for convey~ng the bags 22 between the separator mechan~sm 32 and the fold stat10ns 34, 36 and 38.
Referr~ng to FIGS. 2 and 3, the separator mechan~sm 32 1ncludes an 1nfeed mechan1sm operable to advance the plast1c web at a predeterm1ned speed. In the 111ustrated embod~ment, the 1nfeed mechan~sm compr~ses a pa1F of n1p rollers 42. Oownstream of the nlp rollers 42, the separator mechan1sm 32 further 1ncludes an add1t10nal patr of nlp or separat10n rollers 44, 46. The separat10n rollers 44, 46 operate at a speed h~gher than the 1nfeed n7p rollers 42 and are mounted for rec~procat1ng movement 1nto and out of engagement w1th each other. In part~cular, the upper n~p roller 46 1s mounted on a bracket 48 that, ln turn, p~vots substant1ally up and down relat~ve to the f~xed lower roller 44. The p~vot~ng bracket 48, 1n turn, 1s coupled through an eccentr~c l~nkage 50 to a dr~ve motor 52 so that operat~on of the motor 52 results ~n rectprocat~ng movement of the upper roller 46 1nto and out of engagement w1th the lower roller 44. The lower roller 4 4, ~n turn, 1s coupled through a plural1ty of dr1ve belts 54 to an 1nfeed dr~ve motor 56 that also operates the 1nfeed rollers 42. By reduc~ng the s~ze of the dr1ve pulley 58 coupled to the lower separat10n roller 44, the separat10n rollers 44, 46 operate faster than the 1nfeed rollers 42. In one embod1ment, the separat~on rollers 44, 46 are operated at a speed 25X greater than the speed of the 1nfeed rollers 42. In addtt~on, the separat~on rollers 44, 46 are mounted so that the max~mum gap between the upper and lower separat~on rollers ~s approx~mately one-e~ghth 1nch. When the 1nfeed and separat10n rollers contact the web 12 s1multaneously, the speed d1fferent1al between , .
'.;
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- lo -~- 2 Q ~

the rollers creates a long1tudlnally directed tens10n 1n the web 12. If a 11ne of perforat10ns 60 mark1ng the ~uncture between ad~acent bags 22 1s present between the 1nfeed and separat10n rollers 42, 44 and 46, the tens~on thus developed 1s sufflc1ent to tear the web along the perforat10ns 60 and thus separate the 1nd1v1dual bags 22.
To ensure proper separat10n of the bags 22, lt ~s necessary that the reclprocat~ng movement of the separat10n rollers 44 and 46 1nto engagement w1th each other occurs only when the perforattons 60 between ad~acent bags 22 are properly located between : the 1nfeed and separat10n rollers 42, 44 and 46.
Preferably, to ensure proper track1ng of the separated bags 22 through the rema1nder of the separator/folder mechanlsm 28, the separat10n takes place when the perforat10ns 60 are ad~acent and sl1ghtly downstream of the separat10n rollers 44, 46. To th~s end, the motor 52 for operat1ng the eccentr1c 11nkage 50 1s preferably a servo motor that operates 1n accordance w1th web pos1t10n 1nformat10n der1ved from the upstream bag mak1ng mach1ne 20. In part1cular, a pos1t10n 1nd1cator coupled to the per-foratlng kn~fe 26 of the upstream bag mach~ne 20 pro-v1des web pos1t10n 1nformat10n to the servo motor 52, and the motor 52 then operates to reclprocate the separat10n rollers 44 and 46 so that the rollers engage the web 12 when the next ad~acent downstream web perforat10n 60 1s between the 1nfeed and separat10n rollers 42, 44 and 46.
Referr1ng further to FIGS. 2, 3 and 4, the separator/folder mechan~sm 28 1ncludes three separate fold statlons 34, 36 and 38. Each of the fold ~ stat~ons 1s capable of fold~ng an 1nd1vSdllal bag 22 ~ once along a fold 11ne extend1ng across the w1dth of the bag perpend1cular to the s1de edges thereof. As 2~

~llustrdted~ each fold stat~on 34, 36 and 38 ~ncludes a pa~r of n~p rollers 62, 64 and 66, respect~vely that rotate ~n the direct~ons shown by the arrows ~n FIG. 3. A rope belt conveyor 68 and gu~des 70 and 72 ad~acent each of the fold~ng n~p rolls 62, 64 and 66 funct~ons to transport and gu~de the bags 22 past the ntp rolls. An a~r ~et 74, 76 and 78 ~s located beh~nd the conveyor and gu~des and ~s dtrected through the rope belt and gu~de rods toward the n~p between the foldtng rolls. When the a~r ~et 74, 76 and 78 ~s actuated, the bag 22 carr~ed on the ad~acent conveyor 68 or gu~de 70, 72 ~s tucked between the foldlng rolls 62, 64 and 66 as best seen ~n FIG. 2.
A f~ber opt~c p~ckup scanner 80 mounted ad~acent the conveyor 68 and gu~des 70, 72 senses the lead edge of each bag 22 as ~t travels past. The p~ckup scanner 80 actuates a counter that ttmes actuat~on of the a~r ~ets 74, 76, 78 so that actuat~on occurs when the m~ddle of the bag ~s oppos~te the ~et 74. Th~s causes the bag to be folded ~n half as ~t travels through the fold~ng rollers 62. At the next fold~ng stat~on 36, the process ~s repeated thereby fold~ng the bag ~n half once aga~n. At the next fold~ng stat~on 38, the bag 22 ~s folded ~n half st~ll aga~n. At th~s po~nt, the bag 22 has been folded three tlmes to one-etghth ~ts or~g~nal length. Th~s ~s best seen ~n FIG. 7.
As best seen tn FIG. 4, one roller ~n each pa~r of fold~ng rollers ~s preferably spr1ng loaded so that the fold~ng rollers automat~cally ad~ust to the th~ckness of the bag be~ng folded.
Once the bag passes through the flnal fold~ng -stat~on 38, ~t ~s ready for transfer to the stacker mechan~sm 30. In a htgh speed bag mak~ng operat~on, each bag 22 can be mov~ng at cons~derable speed as ~t passes through the separator/folder mechan~sm 28.
Such h~gh speed can make ~t d~ff~cult to stack the , 2 ~

folded bags 22 w~th accuracy and cons~stency.
Accord~ngly, the separatortfolder 28, ~n accordance w~th one aspect of the ~nvent~on, ~ncludes a slowdown mechan~sm that reduces the speed of each folded bag as ~t ex~ts the separator/folder mechan~sm 28. The slowdown mechan~sm ~ncludes a motor 82 and a pa~r of slowdown wheels 84, 86 coupled to the motor 82 through a two speed clutch mechan1sm 88. When the clutch ts not engaged, the rollers 84, 86 operate at a speed that substant~ally matches the speed of the bags through the separator/folder mechan~sm 28. When the clutch ~s engaged, the speed of the slowdown rollers 84, 86 ~s reduced by approxtmately one-th~rd. An opt~c sensor 90 senses when each folded bag 22 emerges from the thlrd fold~ng stat~on 38. The sensor 90 tr~ggers a counter that controls actuat~on of the clutch so that when approx~mately one-th~rd of the folded bag 22 rema~ns left to pass through the slowdown rolls 84, 86, the slowdown rolls sh~ft to slower speed operat~on. Th1s has the effect of slow~ng the speed at wh~ch the folded bags are d~scharged from the separator/folder mechan~sm 28.
In accordance wlth one aspect of the ~nvent~on, a substant~ally ~amproof convey~ng system 40 ~s prov~ded for convey~ng the bags between the separator mechan~sm 32 and the var~ous fold~ng stat~ons 34, 36 and 38. In the ~llustrated embod1ment, the conveyor 40 compr1ses a plural~ty of w~de t~m~ng belts 92, 94 arranged generally so that the conveyed bags 22 are sandwtched between the upper surface of a lower belt 92 and the under surface of an ad~acent, overly~ng, upper belt 94. Preferably, the upper and lower belts 92 and 94 each compr~se a pa~r of parallel, s~de-by-s~de belts 96, 98 and lO0, 102 separated by a small gap. ~n one , ~a~
embod~ment, each of the belts 96-102 is approx~mately ten ~nches w~de, and the gap between ad~acent belts 96, 98 or lO0, 102 ~s approx~mately one-half ~nch.
Th~s results ~n a convey~ng surface that ~s approx~mately twenty and one-half ~nches w~de9 wh~ch ~s w~der than any of the bags 22 ~ntended to be handled by the part~cular separator/folder 28. As a result, the belts 92, 94 extend under and beyond the s1de marglns of the conveyed bags 22 thereby reduc~ng the 11kel1hood that a bag w~ll wrap around the s1de of the belt and cause a ~am.
In accordance w~th another aspect of the ~nvent~on, the ~amproof conveyor 40 ~s arranged so that relat~ve long~tud~nal movement between the upper and lower belts 92, 94 as the d~rect~on of the belts changes ~s not transferred to or felt by the conveyed bags 22. In part~cular, a change ~n the d~rect~on of the conveyor run ~s ach~eved by runn~ng the upper belt - 94 over a f~rst roller 104 whtle runn~ng the lower belt 92 over a pa~r of add~t~onal rollers 106, 108 that are d~splaced laterally from the f~rst roller 104. When so arranged, the upper and lower belts 92, 94, wh~ch normally l~e ad~acent each other, are separated wh~le they undergo a change ~n d~rect~on.
, By the same token, the belts 92, 94 are only ~n close prox~m~ty to each other when the run of the conveyor 40 ~s substant1ally stra1ght. In operat~on, the conveyed bags 22, whlch ord1nar~1y are sandwlched between the upper and lower belts 92, 94, pass over the f~rst roller 104 and under the overly1ng belts 100, 102, wh~le the underly~ng belts 96, 98 pass over the ~nner rollers 106, 108 wh~le separated from both the bag 22 and the overly~ng belts lO0, 102. After the change of d~rest~on ~s accompl~shed, the belts are once aga~n brought back together. An upwardly ' ';

- 14- ~Q~

d~rected a~r ~et llO, and a downwardly d~rected a~r ~et 112, between the d~splaced rollers ensure that the conveyed bag 22 rema~ns aga~nst the unders~de of the upper belt 94 as ~t passes around the roller 104.
The advantage of th~s roller and belt arrangement ~s that ~t avo~ds bag d~stort~on that m1ght occur ~f the two belts and the bag sandw~ched therebetween were to pass over a slngle roller.
In accordance w~th yet another aspect of the tnventlon, a dancer mechan~sm 114 ~s prov~ded upstream of the ~nfeed rollers 42. The dancer mechan~sm 114 senses tens~on 1n the plast~c web 12 as ~t enters the separator/folder 28 and prov~des feedback to the ~nfeed motor 56 so as to ensure that the ~nfeed speed matches the outfeed speed of the upstream bag mach~ne. A dancer roll 116 has a relat~vely small d~splacement range of only about l/16 to l/8 of an tnch. The small d~splacement range of the dancer 116 avo~ds sh~ft~ng the perforat~on 60 ~n the web relat1ve to the separat~ng rolls 44, 46 as can result when dancers hav~ng a larger dlsplacement are ut~l~zed. Use of the small d~splacement dancer roll 116 avo~ds such sh~ft~ng or phas~ng errors and ensures that the perforat~ons remaln properly located relat1ve to the separat~on rolls 42, 46 dur~ng the separat~ng sequence.
The separator~folder mechantsm frame 1s arranged ~n two parts 118, 120 that are moveable relat~ve to each other around a p~vot 122. The frame members 118, 120 and var~ous rollers are arranged so that, when the frame members are p~voted apart, ad~acent rollers separate along the path followed by the bags 22 through the separatorifolder mechan~sm 28. Th~s makes ~t very easy to clear the mach~ne ~n the event of a 2Q3~8 ~am. Preferably, a user actuated pneumat1c cyl1nder 124 ~s 1ncluded for p~vot~ng the frame halves 118~ 120 relat1ve to each other.
To enhance versatll1ty, the separator/folder 28 can be operated so that the separator mechanlsm 32 operates ~ndependently of the folder mechan~sm 34, 36 38. To thls end, separate motors ~6 and 126 are prov~ded for operat1ng the separat1ng and foldlng sectlons of the machlne. In add~t10n, a downwardly dlrectly a1r ~et 128 ls posltloned ad~acent the downstream end of the separator mechan1sm 32. When actuated, the alr ~et 128 dlverts the separated bags 22 away from the ma1n conveyor 40 and onto the floor below the mach1ne 28. In thls manner, the separator mechanlsm 32 can cont1nue to operate 1n synchron1zat10n w1th the upstream bag mak1ng mach1ne 20 wh11e the folder mechan1sm 1s shut down as, for example, to clear a ~am. Thls avo1ds shuttlng down the entire product10n 11ne lO. An add1t10nal upwardly d1rected a1r ~et 130 funct~ons to d1vert the separated bags 22 once agaln 1nto the ma1n conveyor 40 after the fold1ng mechan1sm has been returned to operat1on.
In accordance wlth sttll another aspect of the 1nvent10n, the separator/folder mechan1sm 28 can be operated so as to provlde one, two or three folds ln the ftnlshed bag. To th1s end, the alr ~ets 74, 76, 78 that d1rect the bags 1nto fold1ng rollers can, optlonally, be actuated when the leading edge, rather than the m~ddle, of a bag 22 ~s opposlte the fold1ng rollers. When the lead1ng edge, rather than the m1ddle, of the bag 1s d1rected through the fold1ng rollers, the bag passes through the rollers unfolded. By operat1ng one, two or three of the a1r ~ets so that the m1ddle, rather than leadlng edge, of the bag 1s d1rected 1nto the fold1ng rollers, one, $
two or three complete folds can be achteved.
S1mtlarly, any one of the a1r ~ets 74, 76 or 78 can be selecttvely deacttvated so that the bag ts not dtrected tnto the fold1ng rollers at all. In such ease, the bag cont~nues past the fold~ng rollers and ts depostted onto the floor. Opt~c sensors (not shown) located at strategtc pos1t~ons 1n the convey1ng path can be used to sense when a bag exceeds normal s1ze 11m1ts or ts otherwtse 1mproperly formed, and th1s 7nformatton can be used to deact1vate the next downstream a1r ~et so that the bag 1s thus dtverted from the normal flow. In thts way, the separator/folder mechan1sm can provtde an automat1c re~ect feature.
The bag stacker mechantsm ts tllustrated tn greater detatl tn FIG8. 8 through 13. As shown, the bag stacker and tndextng conveyor 30 functtons bastcally to stack a predetermtned number of folded bags 22, to compress the bags to reduce the s~ze of a stack 130 of folded bags 22 and to transfer each of the result1ng stacks 130 to a conveyor 132 for further process1ng.
Referrtng to FIGS. 8 and 9, the bag stacker 30 1ncludes a patr of stacktr,g ftnger assembltes 134, 136 on whtch folded bags 22 deltvered by the separator/folder mechan~sm 28 are tntt1ally depostted. The stack1ng f1ngers 134, 136 cooperate wtth a palr of stde gu1des 138, 140, a plural1ty of back stop rods 142 and a front gu1de 144 to def1ne a rectangular chamber for rece1vtng the folded bags 22.
Use of the stde gu1des, back stop rods and front gutde ensures that the bags rema1n perfectly al1gned wtthtn the stack 130.
The two sets of stacktng f1ngers 134, 136 operate 1n a generally rectangular mot~on so that bags stacked onto the stack~ng ftngers are lowered onto the underlytng ~ndex~ng conveyor 146. When a .' . 2~5~8 predeterm~ned number of bags have been accumulated upon one of the stacktng ftnger assembltes 134, 136, that stacktng ftnger assembly lowers the stack onto the conveyor 146 whtle the other stacktng ftnger assembly moves lnto pos~t~on to recetve the next sertes of folded bags del~vered by the separator/folder 28. Conttnuous oepratlon of the stacktng f1ngers tn thls manner avo~ds the need to tnterrupt the flow of folded bags from the separator/folder 28.
After each stack of bags ~s del~vered to the lndex1ng conveyor 14~, the stack 130 ~s next transferred to a compresstng statlon 148 shown tn deta11 tn FIG. lO. The compress~ng statton 148 tncludes a plural~ty of gutdes 150 that support the stdes of the stack 130 and ensure that the bags 22 w1thtn the stack 130 rematn perfectly altgned durtng the compresstng operatton. Preferably, two compress~ng stat~ons are ~ncluded so that each stack 1s compressed twtce to remove alr from between the bags.
Each compress1ng statton tncludes, tn addtt1on to the gutdes 150, a pneumattcally drtven ram 152 connected to a compress1On plate 154. When the ram 152 ts actuated, the plate 154 ~s pressed downwardly onto the top of the stack 130 thereby drtvtng atr from between the bags and reduc1ng the stze of the overall stack 130. After betng compressed at the ftrst compresstng statton, the stack 1s compressed once aga~n at the next downstream statton that operates ~n the same manner.
Downstream of the dual statton compressor, the stacker mechan~sm tncludes a stack transfer mechantsm 156, shown ~n ~IG. 13. The packagtng mach~ne conveyor 132, wh~ch leads downstream to add~t~onal packag~ng mach~nery, ~s located ~ust forward the stack 130. A pa~r of sprockets 160, 162 rotatable around a hor~zontal shaft 164 are pos~tloned beh~nd the stack 130, and an add~t~onal pa~r of sprockets 166, 168, also rotatable around a hor~zontal shaft 170, ~s pos~t~oned forward of the stack 130 over the packag~ng mach~ne conveyor 132. A palr of parallel transfer cha~ns 172 are looped over the opposed sprockets so as to extend above and substanttally parallel to both the stack 130 and the packag~ng mach~ne conveyor 132. A motor 174 ~s coupled through a dr1ve belt 176 to the sprockets thereby driv~ng each transfer cha~n 172 ~n a cont~nuous loop.
Opposed pa~rs of transfer f~ngers 178 are mounted on the parallel transfer cha~ns 172 and extend downwardly beh~nd the stack 130 dur~ng normal c1rculat~on of the cha~ns 172. As the cha1ns conttnue to c~rculate, the transfer f~ngers 178 push the stack 130 onto the packag~ng mach~ne conveyor 132.
The next stack 130 ~s then del~vered to the d~scharge area up aga~nst the stop 158 after wh~ch the next pa~r of transfer f~ngers 1 78 push the stack onto the packag~ng conveyor 132.
Wh11e a part1cular embod1ment of the ~nvent~on has been shown and descr1bed, ~t w111 be obv~ous to those sk~lled ~n the art that changes and mod~f~cat~ons may be made w~thout depart~ng from the ~nvent~on ~n ~ts broader aspects, and, therefore, the a~m ~n the appended cla~ms 1s to cover all such changes and mod~f~cat~ons as fall w~thtn the true sp~r~, and scope of the ~nvent~on.
;

Claims

WE CLAIM:

1. A separator for separating individual sheets from a continuous plastic web having transverse perforations formed therein, said separator comprising:
an infeed mechanism for advancing the plastic web at a predetermined speed;
a pair of nip rollers located downstream of said infeed mechanism and mounted for reciprocating movement into and out of engagement with each other, said nip rollers operating when engaged to advance the plastic web at a speed greater than said predetermined speed so as to cause the continuous plastic web to separate along the next adjacent transverse perforation between said nip rollers and said infeed mechanism;
a linkage including an eccentric coupled to at least one of said nip rollers for reciprocating said nip rollers into engagement with each other in response to rotation of said eccentric; and a motor for rotating said eccentric to reciprocate said nip rollers into engagement with each other and thereby cause the plastic web to separate along the next adjacent downstream perforation.

2. A separator as defined in Claim 1 wherein said motor comprises a servo motor.

3. A separator as defined in Claim 2 wherein said separator further includes means responsive to the position of the continuous plastic web for controlling said servo motor so that said nip rollers are reciprocated into engagement with each other when the next adjacent downstream perforation in the continuous plastic web is adjacent said nip rollers.

4. A separator as defined in Claim 3 wherein said servo motor is coupled to said eccentric through a timing belt.

5. A separator as defined in Claim 2 wherein said means for controlling said servo motor further includes a dancer in contact with the continuous plastic web upstream of said nip rollers for sensing the relative speed of the continuous web.

6. A separator as defined in Claim 5 wherein said dancer is displaceable over a range of substantially one-eighth inch or less.

7. A separator/folder for separating individual sheets from a continuous plastic web having transverse perforations formed therein and for folding the separated individual sheets along at least one predetermined fold line, said separator/folder comprising:
a separator mechanism for separating individual sheets from the continous plastic web;
a plurality of fold stations operable to fold the separated individual sheets along predetermined fold lines; and a plurality of belts for conveying the separated individual sheets among said separator mechanism and said fold stations, each of said belts defining a conveying surface having a width greater than the width of the separated individual sheets and including a continuous side margin that extends beyond the adjacent side margin of the conveying individual sheets.

8. A separator/folder as defined in Claim 7 wherein each of said belts comprises a timing belt having a width greater than substantially one-half the width of the separated individual sheets.

9. A separator/folder as defined in Claim 8 wherein said separator/folder includes a pair of said belts running substantially parallel and adjacent to each other so that one of said belts extends under and beyond one side margin of the conveyed individual sheets and the other of said belts extends under and beyond the other side margin of the conveyed individual sheets.

10. A separator/folder as defined in Claim 9 further comprising additional belts adjacent said two belts for sandwiching the conveyed individual sheets between said two belts and said additional belts.

11. A separator/folder as defined in Claim 9 further including a first motor for operating said separator mechanism and a second motor for operating said belts independently of said separator mechanism.

12. A separator/folder as defined in Claim 11 further comprising means for deactivating said second motor independently of said first motor so that said belts can be stopped while said separator mechanism continues to operate.

13. A separator/folder for separating individual sheets from a continuous plastic web having transverse perforation formed therein and for folding the separated individual sheets along at least one predetermined fold line, said separator/folder comprising:
a separator mechanism for separating individual sheets from a continuous plastic web;

a plurality of fold stations operable to fold the separated individual sheets along predetermined fold lines;
a belt assembly for conveying the separated individual sheets among said separator mechanism and said fold stations, said belt assembly comprising:
a first belt having an undersurface and further having an upper surface for supporting on said upper surface the separated individual sheets;
a second belt having an undersurface overlying said first belt so as to sandwich the separated individual sheets between said upper surface of said first belt and said lower surface of said second belt; and means for simultaneously moving said first and second belts in conjunction with each other so as to transport the separated individual sheets between said first and second belts with substantially no relative longitudinal movement between said upper surface of said first belt and the separated individual sheets and between said lower surface of said second belt and the separated individual sheets;
said moving means including a first roller engaging said lower surface of said first belt and further including a second roller displaced from said first roller and engaging said lower surface of said second belt, said first and second rollers being arranged to change the direction of the said first and second belts and to separate said first and second belts during said change of direction so that relative differences in the longitudinal surface velocities of said first and second belts over said change of direction are not imparted to the conveyed separated individual sheets.

14. A separator/folder as defined in Claim 13 wherein said upper surface of said first belt and said under surface of said second belt are each of greater width than the width of the conveyed, separated, individual sheets.

15. A separator/folder as defined in Claim 14 further including means between said first and second rollers for maintaining the separated, individual sheets in contact with the under surface of said second belt between said first and second rollers.

16. A separator/folder as defined in Claim 15 wherein said maintaining means comprises an air jet directed toward said under surface of said second belt.

17. A separator/folder as defined in Claim 16 wherein said maintaining means comprises a first air jet directed upwardly against the under surface of said second belt upstream of said second roller and further comprises and additional air jet directed downwardly against said under surface of said second belt downstream of said second roller.

18. A separator/folder for separating individual sheets from a continuous plastic web having transverse perforation formed thereon and for folding the separated individual sheets along at least one predetermined fold line, said separator/folder comprising;
a separator mechanism for separating individual sheets from the continuous plastic web;
a plurality of fold stations operable to fold the separated individual sheets along predetermined fold lines;

a belt assembly for conveying the separated individual sheets among said separator mechanism and said fold stations; and a slowdown mechanism positioned downstream of said fold stations for slowing the conveyed speed of the separated individual sheets as the sheets are discharged from said separator/folder;
said slowdown mechanism comprising a pair of nip rolls positioned to engage the separated individual sheets as the sheets are discharged from said separator/folder;
said slowdown mechanism further comprising driving means coupled to said nip rolls for operating said nip rolls at a first predetermined speed when each of the separated individual sheets first engages said nip rolls and for reducing the speed of said nip rolls to a second predetermined speed lower than said first predetermined speed as each of the sheets transits through said nip rolls and for increasing the speed of said of nip rolls to said first predetermined speed prior to engagement of the next following sheet with said nip rolls.

19. A separator/folder as defined in Claim 18 wherein said driving means includes a clutch operable to provide said second predetermined speed lower than said first predetermined speed.

20. A separator/folder as defined in Claim 19 wherein said second predetermined speed comprises substantially one-third of said first predetermined speed.

21. A bag making apparatus comprising:
a rotary bag making machine operable to form a plurality of bags from a continuous plastic web; and a stacker mechanism operable to form stacks of predetermined numbers of the bags, to compress the stacks of bags, and to transfer the compressed stacks to a conveyor.

22. A bag making apparatus comprising:
a rotary bag making machine including a drive motor for actuating said bag making machine, said bag making machine being operable to develop a continuous plastic web having a plurality of bags formed therein;
a separator/folder mechanism operable to separate and fold the bags developed by said bag making machine, said separator folder/mechanism including a drive motor for actuating said separator/folder mechanism;
means associated with said drive motor of said bag machine and with said drive motor of said separator/folder mechanism for synchronizing said separator/folder mechanism to said bag machine so that said separator/folder mechanism separates and folds the bag at a rate matching the rate at which said bag machine develops said bag.